Jack Louis discovered that the Webmin and Usermin "miniserv.pl"
web server component is vulnerable to a Perl format string
vulnerability. Login with the supplied username is logged via the Perl
"syslog" facility in an unsafe manner.

Impact

A remote attacker can trigger this vulnerability via a specially
crafted username containing format string data. This can be exploited
to consume a large amount of CPU and memory resources on a vulnerable
system, and possibly to execute arbitrary code of the attacker's choice
with the permissions of the user running Webmin.